Blood Test Predicts Treatment Response and Survival for Patients with Metastatic Prostate Cancer

10 July 2018

An international team of researchers from Memorial Sloan Kettering Cancer Center (MSK), Epic Sciences, The Institute of Cancer Research, UK, and London Health Sciences Centre, Canada, have shown that a blood test can identify patients with metastatic castration resistant prostate cancer (mCRPC) who may live longer if they switch from targeted androgen receptor-signaling inhibitor (ARSi) therapy, such as enzalutamide and abiraterone, to taxane-based chemotherapy. This independent, multicenter, blinded study is one of the first studies to validate that a liquid biopsy test can predict therapeutic response and demonstrate a survival benefit. The blood test called, Oncotype DX® AR-V7 Nucleus Detect™ is commercially available in the U.S. through Epic Science’s partnership with Genomic Health, Inc. (NASDAQ: GHDX). The research was published online today in JAMA Oncology.

“This liquid biopsy test addresses a critical unmet need at a decision point in management to predict and select the therapy that is most likely to extend a patient’s life,” said Howard Scher, M.D., who led the study and is the co-chair, Center for Mechanism Based Therapy and Head of the Biomarker Development Initiative at MSK. “During the treatment of metastatic prostate cancer, physicians will now be able to use AR-V7 status to determine when a patient’s cancer has become resistant to androgen receptor directed therapy and will respond better to chemotherapy, enabling the patient to live longer.”

This blinded four-year study followed 142 mCRPC patients who were treated at MSK, The Royal Marsden, or the London Health Sciences Centre. Blood samples were obtained prior to treatment with ARSi therapy or chemotherapy and tested with a validated assay for the nuclear-localized androgen receptor splice variant (AR-V7) protein in circulating tumor cells. The results were that patients positive for AR-V7 who were treated with taxane-based chemotherapy had superior overall survival (OS) relative to those treated with ARSI therapy (median OS, 14.3 vs. 7.3 months). Importantly, patients negative for AR-V7 who were treated with ARSi therapy had superior OS relative to those treated with taxanes (media OS, 19.8 vs. 12.8 months). Additionally, the authors validated the test within a prognostic risk group, to ensure that the biomarker effect was due to the biomarker rather than other clinical variables.  

“We developed this test specifically to address a significant clinical question in metastatic prostate cancer that previously had no clear answer: which treatment should be pursued next? This question weighs heavily on doctors and patients, but now, with the Oncotype DX AR-V7 test, we can provide them the confidence to know whether continuing with hormonal therapy or switching to chemotherapy will result in better survival outcomes,” said Ryan Dittamore, chief of medical innovation at Epic Sciences and a co-author on the study. “In addition, the survival benefit gained through the utilization of our AR-V7 test could make the test as valuable to a patient’s outcome as a blockbuster cancer drug."

This is the second blinded, multi-center clinical utility validation study utilizing the nuclear-localized AR-V7 test. Earlier this month, Dr. Andrew Armstrong of Duke Cancer Institute presented data validating the test in the PROPHECY clinical trial at the ASCO 2018 Annual Meeting. The PROPHECY study investigated the AR-V7 test in patients receiving ARSi therapy and demonstrated that patients who tested positive had worse survival by all measures and had no clinical benefit from ARSi therapy. 

In March of this year, based upon earlier studies utilizing the test, Palmetto GBA, a Medicare Administrative Contractor that assesses molecular diagnostic technologies, issued a draft local coverage determination (LCD)for the Oncotype DX® AR-V7 Nucleus Detect™ test.  A full LCD for the test is expected in the upcoming months and would support Medicare reimbursement for applicable patients considering ARSI or taxane therapies.  It is estimated that 50,000 patients a year may be eligible for and benefit from the Oncotype DX® AR-V7 Nucleus Detect™ test.

The paper is entitled, “Assessment of the Validity of Nuclear-Localized Androgen Receptor Splice Variant 7 in Circulating Tumor Cells as a Predictive Biomarker for Castration-Resistant Prostate Cancer.”

About the Oncotype DX® AR-V7 Nucleus Detect™ Test

Designed by Epic Sciences and based on results from multiple studies led by Memorial Sloan Kettering Cancer Center, the Oncotype DX® AR-V7 Nucleus Detect™ test is the first and only liquid biopsy test of its kind that can potentially prolong the lives of men with metastatic castration-resistant prostate cancer (mCRPC) by helping their physician identify the most effective treatment. Through a blood draw, the test detects AR-V7 protein in the nucleus of circulating tumor cells utilizing Epic Sciences' No Cell Left Behind® platform to accurately identify patients who are resistant to androgen receptor (AR)-targeted therapies and who should instead switch to chemotherapy. The Oncotype DX® AR-V7 Nucleus Detect™ test will be performed by Epic Sciences at its centralized, CLIA-certified laboratory in San Diego and offered exclusively by Genomic Health. To learn more about the Oncotype DX AR-V7 Nucleus Detest test, visit www.OncotypeIQ.com and watch this video to learn more.

About Epic Sciences

Epic Sciences, Inc. is developing novel diagnostics to personalize and advance the treatment and management of cancer. Epic Sciences' mission is to enable the rapid and non-invasive detection of genetic and molecular changes in cancer throughout a patient's journey. The company was founded on a powerful platform to identify and characterize rare cells, including circulating tumor cells. Epic Sciences No Cell Left Behind® technology helps match patients to therapies and monitor for drug resistance, so that the best treatment path can be chosen at every clinical decision point. Epic Sciences has partnered with Genomic Health to commercialize the Oncotype DX® AR-V7 Nucleus DetectTM test, which helps with therapeutic decisions between taxane chemotherapy or androgen-directed therapeutics in metastatic castrate-resistant prostate cancer. Today, we partner with leading pharmaceutical companies and major cancer centers around the world. Epic Sciences' goal is to increase the success rate of cancer drugs in clinical trials and improve patient outcomes by providing physicians real-time information to guide treatment choices. Epic Sciences is headquartered in San Diego.

Further information is available on the Company's website, www.epicsciences.com

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